1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to the manufacturing of light emitting devices, and more particularly, to a method of manufacturing light emitting devices, which enables mass production of the light emitting devices while providing high quality and reducing manufacturing costs.
2. Description of the Related Art
Incandescent lamps occupy a large segment of the lamp market. Incandescent lamps emit light of a desired color from among various desired colors by using a filter, for example, in the brake lamp of a car or a traffic light, which requires light of only a single color. In this case, since energy is spent generating unnecessary colors, energy efficiency is greatly reduced.
A light emitting diode (LED), which was introduced in the 1960's, emits light of a single desired color. Accordingly, energy is not spent generating unnecessary colors and energy efficiency can be enhanced. Until recently, LED use has been limited to display lamps or other display devices. However, the LED is now widely used as an interior lamp and a brake lamp of a car, a traffic light, an outdoor electric sign, and a backlight lamp of a cellular phone or PDA, since highly efficient AlGaInP (red) and GaInN (green) LEDs grown by a metal organic chemical vapor deposition (MOCVD) process were developed.
Accordingly, mass production of LEDs is required. However, there are several difficulties in mass production of the LED, and in the course of manufacturing the LED.
Specifically, when a compound semiconductor is separated from a growth substrate of a single crystal in the course of manufacturing an LED, a crack may occur in the compound semiconductor due to factors such as a lattice defect and a difference in thermal expansion coefficients between the compound semiconductor and the growth substrate, whereby production efficiency may be deteriorated.
For example, a GaN substrate can generally be manufactured by using an Al2O3 substrate as a growth substrate. However, if a GaN layer is formed on the Al2O3 substrate, a crystalline defect of high density may occur due to the difference in lattice constants and thermal expansion coefficients between the GaN layer and the Al2O3 substrate. Therefore, a crack occurs in the GaN layer when the GaN layer is being separated from the Al2O3 substrate. Accordingly, production efficiency of the GaN layer may be deteriorated and the quality of the product may also be deteriorated.
In recent manufacturing methods, the GaN layer is separated from the Al2O3 substrate by a laser lift off process which includes irradiating a laser to a transparent Al2O3 substrate after growing the GaN layer on the Al2O3 substrate, and melting a surface portion between the GaN layer and the Al2O3 substrate. However, it is difficult to handle the GaN layer separated by the laser lift off process because such a GaN layer is very thin. Also, as described above, it is likely that the thin GaN layer may be broken due to the difference in thermal expansion coefficients and lattice constants between the GaN layer and the Al2O3 substrate when the GaN layer is being separated from the Al2O3 substrate. For this reason, the crack which occurs in the course of separating the GaN layer from the Al2O3 substrate is adverse to mass production and manufacturing cost, and deteriorates production efficiency.
Accordingly, a light emitting device and a method of manufacturing the same, which enables mass production while providing high quality, and can remarkably reduce manufacturing costs is required.